Safety work benches of this type are generally known, for example from the company brochure "Biological Safety Work Benches/Heraeus Lamin Air HB and HBB" of Heraeus Instruments GmbH. Safety work benches of this type are so constructed that parallel to the work opening a vertically directed air current can be generated which, in the manner of a curtain, prevents the contaminated atmosphere from passing from the working area of the safety work bench to the outside through the work opening. For this purpose, ventilation openings are provided in the basically horizontal boundary plate of the work opening, and through these ventilation openings an air current directed vertically downward is created.
Frequently, it is necessary that manual work be performed for a long period of time at the safety work bench. The person working at the safety work bench is thereby subjected to a relatively high bodily load in the arms. In order to avoid fatigue, especially of the lower arms and hands, the lower boundary plate is hence used as an arm rest for the forearms. For this, the boundary plate can be rounded off on its edge facing outward toward the user. If the boundary plate is used in the manner described as an arm rest, the ventilation openings will be covered by the arms so that a laminar air current is impeded. In this way, the function of this air current is disturbed. Moreover, the boundary plate can only be cleaned at a relatively high cost.
A safety work bench with an arm rest mounted on the lower edge of the work opening is known from GB 2,112,927 A.